Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient ...positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web.
A peptide‐conjugated poly(β‐amino ester) that self‐assembles into micelle‐like nanoparticles is prepared by a convenient and modular supramolecular approach. The polymer–beclin‐1 (P‐Bec1) ...nanoparticles display enhanced cytotoxicity to breast cancer cells through induction of autophagy. This approach overcomes two major limitations of the haploinsufficient tumor suppressor Bec1 compared to small‐molecule drugs: poor delivery to tumors owing to enzymatic degradation, and unstable, non‐specific bio‐distribution and targeting in the tumor tissues.
CuO/graphene composite is synthesized from CuO and graphene oxide sheets following reduced by hydrazine vapor. As the electrode material for lithium-ion batteries, CuO nanoparticles with sizes of ...about 30nm homogeneously locate on graphene sheets, and act as spacers to effectively prevent the agglomeration of graphene sheets, keeping their high active surface. In turn, the graphene sheets with good electrical conductivity server as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during discharge/charge process. The synergetic effect is beneficial for the electrochemical performances of CuO/graphene composite, such as improved initial coulombic efficiency (68.7%) and reversible capacity of 583.5mAhg−1 with 75.5% retention of the reversible capacity after 50 cycles.
Autophagy plays a crucial role in the metabolic process. So far, conventional methods are incapable of rapid, precise, and real-time monitoring of autophagy in living objects. Herein, we describe an ...in situ intracellular self-assembly strategy for quantitative and temporal determination of autophagy in living objectives. The intelligent building blocks (DPBP) are composed by a bulky dendrimer as a carrier, a bis(pyrene) derivative (BP) as a signal molecule, and a peptide linker as a responsive unit that can be cleaved by an autophagy-specific enzyme, i.e., ATG4B. DPBP maintains the quenched fluorescence with monomeric BP. However, the responsive peptide is specifically tailored upon activation of autophagy, resulting in self-aggregation of BP residues which emit a 30-fold enhanced fluorescence. By measuring the intensity of fluorescent signal, we are able to quantitatively evaluate the autophagic level. In comparison with traditional techniques, such as TEM, Western blot, and GFP-LC3, the reliability and accuracy of this method are finally validated. We believe this in situ intracellular self-assembly strategy provides a rapid, effective, real-time, and quantitative method for monitoring autophagy in living objects, and it will be a useful tool for autophagy-related fundamental and clinical research.
Relatively small hysteresis in voltage, appropriate electromotive force and low average delithiation voltage make MnO, among many transition metal oxides. MnO/reduced graphene oxide sheet (MnO/RGOS) ...hybrid is synthesized by a two-step electrode design consisting of liquid phase deposition of MnCO3 nanoparticles on the surface of graphene oxide sheets followed by heat treatment in flowing nitrogen. As an anode for Li-ion batteries, the MnO/RGOS hybrid electrode shows a reversible capacity of 665.5 mA h g−1 after 50 cycles at a current density of 100 mA g−1 and delivers 454.2 mA h g−1 at a rate of 400 mA g−1, which is obviously better than that of bare MnO electrode. Those reasons for such enhanced electrochemical properties are investigated by galvanostatic intermittent titration technique (GITT) as well as electrochemical impedance spectroscopy (EIS). The probable origins, in the term of thermodynamic and kinetic factors, for the marked hysteresis in voltage observed between charge and discharge are also discussed.
► MnO/RGOS hybrid is synthesized by a two-step electrode design. ► As an anode material, it displays superior lithium storage performance. ► Reasons for such enhanced performance are investigated by TEM, GITT and EIS. ► The probable origins of hysteresis in voltage are discussed.
The deposition morphology of a landslide dam determines the position of initial breach and sequentially affects the direction of lateral erosion. Twenty-seven discrete element numerical simulations ...were carried out to investigate the deposition morphology of landslide dams concerning three factors, which include the valley shape, the valley bed inclination and the landslide velocity. The simulation results show that the valley shape and the landslide velocity affect the dam morphology in both transverse and longitudinal directions, while the valley bed inclination mainly affects the longitudinal morphology of dams. Further, a flume experiment was carried out to investigate the specific effects of the dam morphology on the overtopping erosion of landslide dams. The results of experiment show that for the dams in different deposition morphologies and with different initial breaches, the breach widths and the total sediment discharges induced by overtopping erosion are different.
Carbon coated FeS2 (FeS2/C) composite is prepared via a simple solid state reaction using glucose as carbon source. The porous FeS2 particles are uniformly surrounded by the amorphous carbon coating. ...As an anode material for lithium ion batteries, the FeS2/C composite exhibits higher reversible capacity and better cycling performance than the unmodified FeS2. The specific capacity of the FeS2/C composite after 50 cycles is 495 mAh g−1, much higher than that of FeS2 (345 mAh g−1). In order to investigate the effect of carbon coating, the cycled electrodes have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The improvement is attributed to the introduction of carbon coating, which can enhance the conductivity, reduce the dissolution of sulfur and corrosion from HF, and stabilize the porous structure during cycling.
► FeS2/C composite is prepared by a simple solid state reaction for the first time. ► The result of XPS shows the carbon coating can reduce the corrosion from HF. ► The result of ICP shows the carbon coating can reduce the dissolution of sulfur. ► FeS2/C composite shows superior electrochemical performance.
Large pore mesoporous silica nanoparticles (LP-MSNs) functionalized with poly-l-lysine (PLL) were designed as a new carrier material for gene delivery applications. The synthesized LP-MSNs are ...100–200 nm in diameter and are composed of cage-like pores organized in a cubic mesostructure. The size of the cavities is about 28 nm with an entrance size of 13.4 nm. Successful grafting of PLL onto the silica surface through covalent immobilization was confirmed by X-ray photoelectron spectroscopy, solid-state 13C magic-angle spinning nuclear magnetic resonance, Fourier transformed infrared, and thermogravimetric analysis. As a result of the particle modification with PLL, a significant increase of the nanoparticle binding capacity for oligo-DNAs was observed compared to the native unmodified silica particles. Consequently, PLL-functionalized nanoparticles exhibited a strong ability to deliver oligo DNA-Cy3 (a model for siRNA) to Hela cells. Furthermore, PLL-functionalized nanoparticles were proven to be superior as gene carriers compared to amino-functionalized nanoparticles and the native nanoparticles. The system was tested to deliver functional siRNA against minibrain-related kinase and polo-like kinase 1 in osteosarcoma cancer cells. Here, the functionalized particles demonstrated great potential for efficient gene transfer into cancer cells as a decrease of the cellular viability of the osteosarcoma cancer cells was induced. Moreover, the PLL-modified silica nanoparticles also exhibit a high biocompatibility, with low cytotoxicity observed up to 100 μg/mL.
In drug delivery systems, pH‐sensitive polymers are commonly used as drug carriers, and significant efforts have been devoted to the aspects of controlled delivery and release of drugs. However, few ...studies address the possible autophagic effects on cells. Here, for the first time, using a fluorescent autophagy‐reporting cell line, this study evaluates the autophagy‐induced capabilities of four types of pH‐sensitive polymeric nanoparticles (NPs) with different physical properties, including size, surface modification, and pH‐sensitivity. Based on experimental results, this study concludes that pH‐sensitivity is one of the most important factors in autophagy induction. In addition, this study finds that variation of concentration of NPs could cause different autophagic effect, i.e., low concentration of NPs induces autophagy in an mTOR‐dependent manner, but high dose of NPs leads to autophagic cell death. Identification of this tunable autophagic effect offers a novel strategy for enhancing therapeutic effect in cancer therapy through modulation of autophagy.
Using a fluorescent autophagy‐reporting cell, the autophagy‐induced capabilities of four types of pH‐sensitive nanoparticles with variable physiochemical parameters, such as size, surface modification, and pH‐sensitivity are systematically evaluated. The results exhibit that pH‐sensitivity is one of the most important factors in autophagy induction, and that the variation of pH‐sensitivity/concentration of nanoparticles could cause two distinctly different autophagic effects.
Immunotherapy has shown promising treatment effects for a variety of cancers. However, the immune treatment efficiency for solid tumors is limited owing to insufficient infiltration of immune cells ...into solid tumors. The conversion of tumor-supportive macrophages to tumor-suppressive macrophages, inducing the functional reversal of macrophages, is an effective method and contributes to a subsequent antitumor response. The current challenge in the field is the poor distribution and systemic side effects associated with the use of cytokines. As a solution to this issue, we designed and synthesized microenvironment-responsive nanoparticles (P) with IL-12 payload (IL-12⊂P1). These nanoparticles could promote the systemic administration and release of IL-12 in the tumor microenvironment, and the locally responsive property of IL-12⊂P1 could subsequently re-educate tumor-associated macrophages (TAMs). In particular, our results illustrated the great therapeutic effects derived from the functional conversion of macrophages. Our strategy was to design a microenvironment-responsive material for local macrophage modification to overcome the physiological barrier of solid tumors. The shifting of macrophage phenotypes via IL-12⊂P1 achieved immunomodulation in the microenvironment for cancer therapy, with negligible cytotoxicity. We expect that the functional regulation of TAMs by pH-responsive nanomaterials is a promising therapeutic approach for cancer immunotherapy.
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